Viral Pneumonia Flashcards
How is atypical viral pneumonia characterized?
-patchy inflammatory changes in the lungs, largely confined to the alveolar septa and interstitium and mononuclear cell infiltrates in alveolar walls
Is consolidation a common finding of viral pneumonia?
No
Are white cell counts elevated in viral pneumonia
Moderately
Nearly all viruses that cause pneumonia can also cause ____
URTIs
What is the most common cause of RT infection that results in physician visits and hospitalizations in the U.S.?
Influenza
Describe Influenza
Helical, enveloped single stranded negative sense linear RNA virus
What are the major virulence determinants of Influenza?
- Hemagglutinin (promotes viral entry)
- Neuraminidase
- M2 ion channel
What does Neuraminidase do?
cleaves neuraminic acid to release progeny virus from the infected cell and degrades the protective layer of mucus in the RT (2 types - N1, N2)
Which type of Influenza is responsible for pandemics and epidemics?
A
What causes Influenza epidemics?
-Antigenic drift
What is antigenic drift?
spontaneous mutations in the viral genome as it replicates results in new viral strains
What causes Influenza pandemics?
antigenic shift
What is antigenic shift?
Occurs when both HA and NA genes are replaces through reassortment with animal influenza viruses
How is Influenza transmitted?
airway respiratory droplets
How is Influenza treated?
Pseltamivir or Zanamivir
What are the complications of Influenza?
- Secondary viral or bacterial pneumonia
- Reye’s syndrome
What patient populations are at risk for secondary viral or bacterial pneumonia?
- young/elderly
- chronic disease patients
- immunosuppressed
- pregnant
- obese
What nationality is at risk for secondary viral or bacterial pneumonia?
Native Americans or Alaskans
What is Reye’s syndrome characterized by?
encephalopathy and liver degeneration (aspirin is a cause)
Vaccine for Influenza
- Trivalent or quadrivalent
- everyone 6 months or older
- protection lasts 6 months
Prophylaxis for Influenza
Oseltamivir
Respiratory syncytial virus (RSV) belongs to what family?
Paramyxovirus
Describe RSV
pleomorphic, enveloped, negative-sense single stranded, linear RNA
RSV is the most important cause of bronchiolitis and pneumonia in what patients?
infants
How is RSV transmitted?
- Respiratory droplets
- Direct contact of contaminated hands with nose or mouth
- Community outbreaks every winter
Infection of RSV in infants typically involves what part of the RT?
lower
How does RSV present?
- persistent cough
- wheezing
- FEVER
- tachypnea
- hypoxemia
Describe infection of RSV in adults
typical URT (lasts 4-5 days and self-limiting)
How is RSV diagnosed?
- Rt-PCR on nasal swab
- Rapid antigen test on nasal swab or washings
How is RSV treated?
- supportive care (hydration, albuterol, and O2)
- Inhaled Ribavirin (not for children)
Prophylaxis of RSV in premature infants?
Palvizumab (monoclonal Ab against F protein)
Complications of RSV?
- apnea and respiratory failure in preemies, less than 12 weeks of age, CV disease)
- development of asthma
Describe adenovirus
non-enveloped, double stranded, linear DNA virus
How is adenovirus transmitted?
aerosol droplets, fecal-oral, or direct inoculation
What are some diseases that adenovirus can cause?
- pneumonia
- URTI
- febrile pharyngitis
- conjunctivitis (pink eye)
- hemorrhagic cystitits
- gastroenteritis in -2 yoa
How is adenovirus infection treated?
supportive (self-limited)
What is the vaccine for adenovirus?
-live PO enteric-coated vaccines against serotypes 4 and 7 for military recruits
Sequelae of adenovirus?
bronchiectasis or bronchiolitis obliterans
Describe parainfluenza virus structure
enveloped single stranded linear non-segmented RNA virus of the paramyoxiviridae family
Virulency determinants of parainfluenza virus
- F (fusion) protein
- HN (hemagglutinin/neuraminidase)
How is parainfluenza virus transmitted?
respiratory droplets
There are four kinda of PIV. Which types can cause croup?
only 1,2, and 3 (but only 2-3% progress to croup)
hPIV3 can cause what diseases?
pneumonia and bronciolitis
hPIV4 can cause what disease?
mild respiratory illness (common cold)
Croup (aka laryngotracheaobronchitis) is characterized by what?
-seal-like, barking cough caused by inflammation around the larynx, trachea, and bronchi
- fever, sore throat
- stridor
- rhinorrhea
What is stridor?
harsh vibrating noise when breathing caused by obstructions/inflammation of the larynx
T or F. Re-infection of PIV is common
T.
What is a ‘steeple sign’?
inflection of the trachea in stridor caused by inflammation
Human metapneumovirus is indistinguishable from what?
RSV
Describe SARS
coronavirus family-enveloped single stranded positive sense RNA virus
common in Asia
What are the possible reservoirs of SARS?
masked palm civet
horseshoe bat
How does SARS present
- fever/chills
- rigors
- headache
- dyspnea and hypoxemia
- nonproductive cough
CBC findings of SARS?
leukopenia and thrombocytopenia
CXR of SARS
bilateral peripheral infiltrates common usually in middle or lower lung zones
How is MERS transmitted?
human to human
Clinical presentation of MERS
- severe illness with pNA and ARDS, some with AKI
- hemoptysis
- abdominal pain
- sore throat, fever, chills, SOB
